Use of a composition in stereolithography

ABSTRACT

The use of a compound of formula (A), which comprises a group of sub-formula (I) where R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , X 1  and Y 1  are various specified organic groups wherein at least one of said groups has sufficient electron whitdrawing properties to activate the multiple bonds to polymerisation, in a stereolithographic composition. Stereolithographic applications of these compounds are also described and claimed.

[0001] The present invention relates to the use of certain photocurablecompounds in stereolithography, as well as to stereolithographiccompositions containing these compounds, stereolithographic methodsusing these compounds and products obtained thereby.

[0002] The use of stereolithography processes for producingthree-dimensional objects is well known. Broadly speaking, in theseprocesses, a requisite amount of controlled light energy is applied to aliquid photocurable resin to harden the irradiated resin. This may bedone in a series of steps, each of which forms a thin layer of hardenedresin on top of a base layer. A layer of liquid photocurable resin isapplied to a hardened layer and then irradiated under control to hardenthe resin in the form of a thin layer which is integrally superposed onthe previously formed layer. This process can be repeated until adesired solid three-dimensional object is built up.

[0003] Examples of modified stereolithography techniques and theirapplications are described for example in JP-A-60-247515, JP-A-62-35966,JP-A-1-204915, JP-A-1-213304, JP-A-2-28261 and U.S. Pat. No. 5,849,459.

[0004] A typical and commonly used process for producing athree-dimensional object by stereolithography comprises selectivelyapplying a computer-controller ultraviolet (UV) laser beam to thesurface of a liquid photohardenable resin composition. The liquid iscontained in a container and the laser beam is focused so as to hardenthe resin to a predetermined depth (thickness) so as to form a desiredshape. Subsequently liquid resin composition can be applied to thehardened layer to the thickness corresponding to one layer, and a UVlaser beam applied to it so as to form a successive hardened layer onthe preceding layer. Again, this procedure can be repeated until athree-dimensional object having the required dimensions and shape hasbeen built up. This process allows three-dimensional objects havingcomplicated shapes to be obtained easily in a relatively short time.

[0005] With the recent broadening of application of stereolithographyfrom concept models to test models and trial products, there has been anincreasing demand to provide three-dimensional objects having stillhigher dimensional accuracy and dimensional stability. The objects havealso been demanded to have excellent mechanical properties.

[0006] Photohardenable resin compositions generally used instereolithography comprise at least one photo-polymerisable compound,such as a photo-polymerisable modified urethane (meth)acrylate compound,an oligoester acrylate compound, an epoxyacrylate compound, an epoxycompound, a polyimide compound, an aminoalkyd compound, or a vinyl ethercompound, as a main component, and a photosensitive polymerizationinitiator.

[0007] The polymerization of diallyamines using free radical initiationis known, for example from Solomon et al., J. Macromol. Sci.—RevMacromol. Chem. c15 (1) 143-164 (1976). Free radical initiation ofpolymerization requires quite extreme reaction conditions which can begenerated only in production plants etc. It is not suitable forsituations where in situ polymerization is required.

[0008] Other cyclopolymerization reactions are discussed by C. D. McLeanet al., J. Macromol. Sci.—Chem., A10(5), pp857-873 (1976). Yet furtherreactions are described in WO 97/16504, WO 97/16472 where such reactionsare used in a specialised way in the production of liquid crystalcompounds.

[0009] Copending International Patent Application No. WO 00/06610describes methods of producing polymeric compounds, in particular usingradiation curing such ultraviolet or thermal radiation, or chemicalcuring or electron beam initiated curing. Certain compounds which formpolymers under the influence of u.v. light form a further aspect of theinvention, as well as to polymers, coatings and adhesives obtainedthereby.

[0010] In these applications, a broad range of compounds with at leasttwo appropriately positioned multiple bonds and in particular doublebonds, may be activated by the presence of an electron withdrawinggroup, in particular where the electron withdrawing group is at aposition which is alpha, beta or gamma to one or both of the doublebonds to make them readily polymerisable under the influence of interalia radiation. The term “readily polymerisable” means that thecompounds will undergo polymerization under moderate conditions oftemperature and pressure (for example at room temperature andatmospheric pressure) in the presence of radiation and an initiator, ina period of less than 24 hours.

[0011] Polymeric compounds obtained therefrom include cyclic rings.These have many advantageous properties. In particular, compounds ofthis type can be used to generate products such as adhesives (seecopending WO 00/06658), coatings, network polymers or conductingpolymers (see copending WO 00/06533) depending upon the other aspects ofthe structure of the starting materials.

[0012] The applicants have found that many of these compounds areparticularly applicable for use in stereolithographic processes.

[0013] Specifically, the invention provides the use of a compound offormula (A), which comprises a group of sub-formula (I)

[0014] where R¹ is CR^(a′) where R^(a′) is hydrogen or alkyl, and R⁶ isa bond, or R¹ and R⁶ together form an electron withdrawing group;

[0015] R² and R³ are independently selected from (CR⁷R⁸)_(n), or a groupCR⁹R¹⁰, CR⁷R⁸CR⁹R¹⁰ or CR⁹R¹⁰CR⁷R⁸ where n is 0, 1 or 2, R⁷ and R⁸ areindependently selected from hydrogen or alkyl, and either one of R⁹ orR¹⁰ is hydrogen and the other is an electron withdrawing group, or R⁹and R¹⁰ together form an electron withdrawing group, and R⁴ and R⁵areindependently selected from CH or CR¹¹ where R¹¹ is an electronwithdrawing group;

[0016] the dotted lines indicate the presence or absence of a bond, andX¹ is a group CX²X³ where the dotted line bond to which it is attachedis absent and a group CX² where the dotted line bond to which it isattached is present, Y¹ is a group CY²Y³ where the dotted line bond towhich it is attached is absent and a group CY² where the dotted linebond to which it is attached is present, and X², X³, Y² and Y³ areindependently selected from hydrogen and fluorine;

[0017] provided that at least one of (a) R¹ and R⁶ or (b) R² and R³ or(c) R⁴ and R⁵ includes an electron withdrawing group which is able toactivate a cyclopolymerization reaction under the influence of radiationused in a stereolithographic process optionally in the presence of aphotoinitiator; in a stereolithographic composition.

[0018] Conditions under which polymerization will occur are those whichare used in stereolithography and include the influence of radiationsuch as u.v. or laser generated radiation or an electron beam.

[0019] Compounds of formula (A) may comprise one or more groups ofsub-formula (I) which may be attached to a variety of organic groups.Where the compound of formula (A) includes more than one group ofsub-formula (I), these may be connected directly to each other orinterposed by various bridging groups as described below.

[0020] The following description of the invention refers to the attachedFigures in which:

[0021]FIG. 1FIG. 1 illustrates the polymerization which may be used inaccordance with the invention; and

[0022]FIG. 2 shows a general scheme whereby cross-linking to formnetwork polymers may occur.

[0023] In particular X¹ and Y¹ are groups CX²X³ and CY¹Y² respectivelyand the dotted lines represent an absence of a bond. Thus preferredcompounds are compounds of formula (B) which include a group ofsub-formula (IA)

[0024] where R¹, R², R³, R⁴, R⁵, R⁶, X², X³, Y² and Y³ are as definedabove.

[0025] Suitably there are no more than five atoms in between or linkingthe double bonds in the group of sub-formula (IA) in the startingmaterial so that when the cyclopolymerization takes place, for exampleas illustrated hereinafter in FIG. 1, the size of the rings formed doesnot exceed 7. Preferably, there are from 3 to 5 atoms in between thedouble bonds.

[0026] As used herein, the term “alkyl” refers to straight or branchedchain alkyl groups, suitably containing up to 20 and preferably up to 6carbon atoms. The term “alkenyl” and “alkynyl” refer to unsaturatedstraight or branched chains which include for example from 2-20 carbonatoms, for example from 2 to 6 carbon atoms. Chains may include one ormore double or triple bonds respectively. In addition, the term “aryl”refers to aromatic groups such as phenyl or naphthyl.

[0027] The term “hydrocarbyl” refers to any structure comprising carbonand hydrogen atoms. For example, these may be alkyl, alkenyl, alkynyl,aryl such as phenyl or napthyl, arylalkyl, cycloalkyl, cycloalkenyl orcycloalkynyl. Suitably they will contain up to 20 and preferably up to10 carbon atoms. The term “heterocyclyl” includes aromatic ornon-aromatic rings, for example containing from 4 to 20, suitably from 5to 10 ring atoms, at least one of which is a heteroatom such as oxygen,sulphur or nitrogen. Examples of such groups include furyl, thienyl,pyrrolyl, pyrrolidinyl, imidazolyl, triazolyl, thiazolyl, tetrazolyl,oxazolyl, isoxazolyl, pyrazolyl, pyridyl, pyrimidinyl, pyrazinyl,pyridazinyl, triazinyl, quinolinyl, iosquinolinyl, quinoxalinyl,benzthiazolyl, benzoxazolyl, benzothienyl or benzofuryl.

[0028] The term “functional group” refers to reactive groups such ashalo, cyano, nitro, oxo, C(O)_(s)R^(a), OR^(a), S(O)_(t)R^(a),NR^(b)R^(c), OC(O)NR^(b)R^(c), C(O)NR^(b)R^(c), OC(O)NR^(b)R^(c),—NR⁷C(O)_(s)R⁶, —NR^(a)CONR^(b)R^(c), —C═NOR^(a), —N═CR^(b)R^(c),S(O)_(t)NR^(b)R^(c), C(S)_(s)R^(a), C(S)OR^(a), C(S)NR^(b)R^(c) or—NR^(b)S(O)R^(a) where R^(a), R^(b) and R^(c) are independently selectedfrom hydrogen or optionally substituted hydrocarbyl, or R^(b) and R^(c)together form an optionally substituted ring which optionally containsfurther heteroatoms such as S(O)_(s), oxygen and nitrogen, s is aninteger of 1 or 2, t is 0 or an integer of 1-3. In particular thefunctional groups are groups such as halo, cyano, nitro, oxo,C(O)_(s)R^(a), OR^(a), S(O)_(t)R^(a), NR^(b)R^(c), OC(O)NR^(b)R^(c),C(O)NR^(b)R^(c), OC(O)NR^(b)R^(c), —NR⁷C(O)_(s)R⁶, —NR^(a)CONR^(b)R^(c),—NR^(a)CSNR^(b)R^(c), —C═NOR^(a), —N═CR^(b)R^(c), S(O)_(t)NR^(b)R^(c), ,or —NR^(b)S(O)_(t)R^(a) where R^(a), R^(b) and R^(c), s and t are asdefined above.

[0029] The term “heteroatom” as used herein refers to non-carbon atomssuch as oxygen, nitrogen or sulphur atoms. Where the nitrogen atoms arepresent, they will generally be present as part of an amino residue sothat they will be substituted for example by hydrogen or alkyl.

[0030] The term “amide” is generally understood to refer to a group offormula C(O)NR^(a)R^(b) where R^(a) and R^(b) are hydrogen or anoptionally substituted hydrocarbyl group. Similarly, the term“sulphonamide” will refer to a group of formula S(O)₂NR^(a)R^(b).

[0031] The nature of the electron withdrawing group or groups present inthe group of sub-formula (I) in any particular compound of formula (A)will depend upon its position in relation to the double bond it isrequired to activate, as well as the nature of any other functionalgroups within the compound.

[0032] In a-preferred embodiment, R¹ and R⁶ form an electron withdrawinggroup.

[0033] For example, R¹ is a heteroatom or a substituted heteroatom whichhas electron withdrawing properties and R⁶is a bond. Examples of R¹ inthis instance include groups N⁺R¹²(Z^(m−))_(1/m), S(O)_(p)R¹³, B,P(O)_(q)R¹⁴ or Si(R¹⁵) and in particular a group N⁺R¹²(Z^(m−))_(1/m),S(O)_(p)R¹³, B, P(O)_(q)R¹⁴ where R¹², R¹³, R¹⁴ and R¹⁵ areindependently selected from hydrogen or hydrocarbyl, Z is an anion ofcharge m, p is 0, 1 or 2, and q is 1. Alternatively, R¹ is a group CHand R⁶ is a group —C (O)O— or —OC(O)—.

[0034] In a particularly preferred embodiment, R¹ is a groupN⁺R¹²(Z^(m−))_(1/m), S(O)_(p)R¹³, B, P(O)_(q)R¹⁴ or Si(R¹⁵), andpreferably N⁺R¹²(Z^(m−))_(1/m), S(O)_(p)R¹³, B, or P(O)_(q)R¹⁴ whereR¹², R¹³, R¹⁴ and R¹⁵ are independently selected from hydrogen or alkylin particular C₁₋₃alkyl, and Z is an anion, preferably a halide. Inparticular R¹ is a group N^(+R) ¹²(Z^(m−))_(1/m), and R⁶ is a bond.

[0035] The nature of the anion Z will affect the properties of the finalpolymer and in particular, its conductivity, porosity and waterpermability. Suitable anions for the Z group include halide ions such asfluoride, chloride, bromide or iodide, borides such as borontetrafluoride; carboxylic acid esters such as those of formula R¹⁴C(O)O⁻where R¹⁴ is an optionally substituted hydrocarbyl group group such ashaloalkyl, in particular trifluoromethyl; and other cationic groups suchas mesylate and tosylate. In general, the water permeability of theultimate polymer will vary as follows:

PF₆ ⁻<BF₄ ⁻<CF₃SO₃ ⁻<CF₃COO⁻<NO₃ ⁻<SO₄ ^(2−<I) ⁻<Br⁻<Cl⁻

[0036] Other factors which affect the water permeability of the polymeris the nature of any group to which the group of sub-formula (I) isattached. When this contains for example perhaloalkyl substituents suchas perfluoroalkyl, it will be largely water impermeable as compared topolymers which have alkylene bridging groups optionally interposed withsay oxygen. Examples of such groups are given below.

[0037] Most preferably, the combination of R¹ and R⁶ forms an amidegroup, where R¹ is a nitrogen atom and R⁶ is a carbonyl group. In afurther preferred embodiment, R¹ and R⁶ together form a sulphonamidegroup where R¹ is a nitrogen atom and R⁶ is an S(O)₂ group.

[0038] Alternatively, where the activation is effected by electronwithdrawing groups at a position indicated by R² or R³, suitableelectron withdrawing groups R⁹ and R¹⁰ include nitrile, trifluoromethyl,acyl such as acetyl or nitro, or preferably R⁹ and R¹⁰ together with thecarbon atom to which they are attached form a carbonyl group.

[0039] Where R¹¹ is an electron withdrawing group, it is suitably acylsuch as acetyl, nitrile or nitro.

[0040] Preferably X², X³, Y² and Y³ are all hydrogen.

[0041] Suitable groups R^(a′) include hydrogen or methyl, in particularhydrogen.

[0042] A preferred group of the compounds of formula (A) are compoundsof structure (II)

[0043] and in particular a compound of formula (IIA)

[0044] where X¹, X², X³, Y¹, Y², Y³, R¹, R², R³, R⁴, R⁵, R⁶ and thedotted bonds are as defined in relation to formulae (I) and (IA) above,r is an integer of 1 or more, and R¹⁶ is a bridging group, an optionallysubstituted hydrocarbyl group, a perhaloalkyl group or an amide, ofvalency r.

[0045] Where in the compound of formula (II) or (IIA), r is 1, compoundscan be readily polymerized to form a variety of polymer types dependingupon the nature of the group R¹⁶. Examples of groups which are commonlyfound in polymer technology is included below in Table 1. (In the caseof these compounds however, the bridging groups will terminate forexample by addition of a hydrogen or alkyl group.)

[0046] Monomers of this type may be represented as structure (III)

[0047] where X¹, Y¹, R¹, R², R³, R⁴, R⁵, R⁶ and the dotted lines are asdefined above, and R^(16′) is an optionally substituted hydrocarbylgroup, a perhaloalkyl group or an amide.

[0048] A particular example of such a compound is a compound of formula(IIIA)

[0049] where X², X³, Y², Y³, R¹, R², R³, R⁴, R⁵ and R⁶ are as defined inrelation to formula (I) above, and R^(16′) is as defined in relation toformula (III).

[0050] Preferably in the compounds of formula (III) or (IIIA) as above,R¹ and R⁶ form an electron withdrawing group. Suitably then R² and R³are groups (CR⁷R⁸)_(n) and R⁴ and R⁵ are CH groups. In one embodiment,R¹⁶ comprises a hydrocarbyl group, optionally substituted by afunctional group. Preferably R⁷ includes an unsaturated moiety, such asan aryl or alkenyl group, or a carbonyl substituent.

[0051] A class of compounds of formula (III) is those of formula (IV)

[0052] where R^(16′) is as defined above, and is in particular anoptionally substituted alkyl, alkenyl, alkynyl or aryl group, whereinthe optional substituents may be selected from halogen, hydroxy, carboxyor salts thereof or acyloxy.

[0053] Alternatively, R^(16′) in formula (IV) may comprise aperhaloalkyl group, for example of from 1 to 3 carbon atoms such as aperhalomethyl group, in particular perfluoromethyl.

[0054] Another group for R^(16′) in formula (IV) is a dialkenylsubstituted amide, for example of sub formula (V)

[0055] where R¹⁸ and R¹⁹ are selected from groups defined above for R²and R³ in relation to formula (I), and are preferably —CH₂- or—CH₂CH₂-groups; and R²⁰ and R²¹ are selected from groups defined aboveas R⁴ and R⁵ in relation to formula (I) and are preferably —CH— groups.Such groups would further activate the double bonds and give rise to thepossibility of forming cross-linked polymer networks during thestereolithography process.

[0056] Another class of compound of formula (II) is represented byradiation curable compounds of formula (VI)

[0057] where Z and m are as defined above, R²² and R²³ are independentlyselected from hydrogen and hydrocarbyl, such as alkyl and alkenyl, inparticular prop-2-enyl or hydroxyethyl.

[0058] The invention may also be applied to other sorts of polymers, forexample, where in the compounds of formula (II), r is greater than one,polymerization can result in polymer networks. Particular examples arecompounds of formula (II) as defined above, where R¹⁶ is a bridginggroup and r is an integer of 2 or more, for example from 2 to 8 andpreferably from 2-4.

[0059] On polymerization of these compounds, networks are formed whoseproperties may be selected depending upon the precise nature of the R¹⁶group, the amount of chain terminator present and the polymerizationconditions employed. Polymerization will occur in accordance with thegeneral scheme set out in FIG. 1 hereinafter.

[0060] Suitably r is an integer of from 2 to 6, preferably from 2 to 4.

[0061] The properties of the polymer obtained in this way will dependupon a variety of factors but will depend very largely on the nature ofthe group R¹⁶.

[0062] Suitably R¹⁶ will comprise bridging groups for example as isknown in polymer chemistry. These may include straight or branched chainalkyl groups, optionally substituted or interposed with functionalgroups or siloxane groups such as alkyl siloxanes. Suitable bridginggroups include those found in polyethylenes, polypropylenes, nylons, aslisted in Table 1. TABLE 1 Polymer type Repeat Unit of Bridging GroupPolyethylene CH₂ Polystyrene CH₂CH(C₆H₅) where the phenyl ring isoptionally substituted Polyisobutylene CH₂CH(CH(CH₃)₂) PolyisopreneCH₂CH(CH₃) Polytetrafluoroethylene CH₂(CF₂)_(x)CH₂Polyvinylidenefluoride CH₂(CF₂CH₂)_(x) polyethyleneoxide(OCH₂CH(CH₃))_(x)O Nylon CH₂(NHCOCH₂)_(x)CH₂ PeptideCH₂(NHCOCH_(R))_(x)CH₂ Polyurethanes —NH—CO—O— Polyesters —RC(O)OR′—where R and R′ are organic groups such as hydrocarbyl Polysiloxanes e.g.—SiO₂—, —R₂SiO— or —R₂Si₂O₃— where R is an organic group such ashydrocarbyl Polyacrylates —CH₂C(COOH)H— Polyureas —NHCONH— Polythioureas—NH—C(S)—NH—

[0063] The length of the bridging group will affect the properties ofthe polymeric material derived from this. This can be used to designpolymers with properties which are best suited to the application. Forinstance when the bridging group comprises relatively long chains, (forexample with in excess of 6 repeat units, for example from 6-20 repeatunits), the polymer will have pliable plastic properties. Alternatively,when the bridging group is relatively short, (e.g. less than 6 repeatunits) the material will be more brittle.

[0064] Thus, for example, a compound of formula IIA where the bridginggroup is of the polyethylene type and r is 2 will comprise a compound offormula (IIB)

[0065] where X², X³, Y², Y³, R¹, R², R³, R⁴, R⁵ and R⁶ are as definedabove and each group X², X³, Y², Y³, R¹, R², R³, R⁴, R⁵ and R⁶ may bethe same or different to any other group, and d is an integer of from6-20.

[0066] Another method for producing particular properties of the productarises from the possibility of producing copolymers where anothermonomeric compound, for example one which is not of formula (I), ismixed with the compound of formula (I) prior to polymerization. Suchmonomers are known in the art.

[0067] Examples of possible bridging groups R¹⁶ where r is 2 are groupsof sub-formula (VII)

-13 Z¹—(Q¹)_(a)—(Z²—Q²)_(b)—Z³—  (VII)

[0068] where a and b are independently selected from 0, 1 or 2, Z¹, Z²and Z³ are independently selected from a bond, an optionally substitutedlinear or branched alkyl or alkene chain wherein optionally one or morenon-adjacent carbon atoms is replaced with a heteroatom or an amidegroup, Q¹ and Q² are independently selected from an optionallysubstituted carbocylic or heterocyclic ring which optionally containsbridging alkyl groups.

[0069] Suitable carbocyclic rings for Q¹ and Q² include cycloalkylgroups for example from 1 to 20 carbon atoms. Bridged carbocylic ringstructures include 1,4-bicyclo[2.2.2] octane, decalin,bicyclo[2.2.1]heptane, cubane, diadamantane, adamantane. Suitableheterocyclic rings include any of the above where one or more nonadjacent carbon atoms are replaced by a heteroatom such as oxygen,sulphur or nitrogen (including amino or substituted amino), or acarboxyl or an amide group. Suitable optional substitutents for thegroups Q¹and Q² include one or more groups selected from alkyl, alkenyl,alkynyl, aryl, aralkyl such as benzyl, or functional groups as definedabove. Substitutents for the groups Q¹ and Q² are oxo and halogen inparticular fluorine and chlorine.

[0070] Suitable optional substituents for the alkyl and alkene groupsZ¹, Z² and Z³ include aryl, aralkyl and functional groups as definedabove. Particular substituents include halogen such as fluorine andchlorine, and oxo.

[0071] Other sorts of bridging groups R¹⁶ include electricallyconducting chains, for instance, electrically conducting unsaturatedchains such as alkenes or chains incorporating aromatic or heterocyclicrings. For instance, the group R¹⁶ may comprise a tetra substitutedconducting unit such as a tertathiafulvalene. Thus an example of such acompound is a compound of formula (VIII)

[0072] where R²⁸, R²⁹, R³⁰ and R³¹ are each groups of sub-formula (IX)

[0073] where R¹, R², R³, R⁴, R⁵ and R⁶ are as defined in relation toformula (I) above and R²⁴, R²⁵, R²⁶ and R²⁷ are independently selectedfrom groups of sub-formula (VII) as given above. In particular R²⁴, R²⁵,R²⁶ and R²⁷ are alkyl groups.

[0074] Polymerization of compounds of formula (VIII) will givecross-linked networks where the cross-linking occurs through the doublebonded units. This will lead to a very stable material with robustphysical properties. Once again, varying the length of the spacer groupsR²⁴, R²⁵, R²⁶ and R²⁷ will lead to materials with designer properties.For instance when R²⁴, R²⁵, R²⁶ and R²⁷ are relatively long chains, thepolymer will have pliable plastic properties. Alternatively, when thechains R²⁴, R²⁵, R²⁶ and R²⁷ are relatively short, the material will bemore brittle.

[0075] Where R¹ and R⁶ together form a group —N⁺R⁷Z⁻, varying thecounter ion Z⁻ can also be used to adjust the physical properties of thepolymer, such as water retention, porosity or conductivity. Suitablysubstituted materials will exhibit conducting properties, making themsuitable as organic semiconductors for example for use as interconnectsfor IC chips etc.

[0076] Alternatively, a bridging group R¹⁶ may comprise a tetra or octasubstituted non-linear optic unit such as an optionally substitutedporphyrin or phthalocyanine wherein the optional substitutents includehydrocarbyl groups as well as groups of sub formula (I). An example ofsuch a porphyin compound is a compound of formula (X)

[0077] where R²⁴, R²⁵, R²⁶, R²⁷ R²⁸, R²⁹, R⁺and R³¹ are as defined inrelation to formula (VIII) above and R³², R³³, R³⁴ and R³⁵ are eachindependently selected from hydrogen or hydrocarbyl groups; and thecompound optionally contains a metal ion within the macrocyclicheterocyclic unit.

[0078] An alternative phthalocyanine compound is a compound of formula(XA)

[0079] where R⁵⁰ through to R⁶⁵ are independently selected fromhydrocarbyl in particular C₁₋₁₂ alkyl, a group OR⁶⁸ where R⁶⁸ ishydrocarbyl in particular butyl, halogen in particular chlorine or agroup R²⁴-R²⁸ where R²⁴ and R²⁸ are as defined in relation to formula(VIII) above, provided that at least two of R⁵⁰ to R⁶⁵ are R²⁴-R²⁸groups, and R⁶⁶ and R⁶⁷ are either hydrogen or together comprise a metalion such as a copper ion.

[0080] Preferably in formula (XA), R⁵¹, R⁵², R⁵⁵, R⁵⁶, R⁵⁹, R⁶⁰, R⁶³ andR⁶⁴ are halogen and R⁵⁰, R⁵³, R⁵⁴, R⁵⁷, R⁵⁸, R⁶¹, R⁶² and R⁶⁵ areindependently C₁₋₁₂ alkyl, C₁₋₁₂ alkoxy or a group R²⁴-R²⁸.

[0081] Polymerization of a compound of formula (X) or (XA) duringstereolithography in accordance with the scheme of FIG. 1, will providea cross linked network polymer where the cross linking occurs throughthe diene units for example as either quaternery ammonium salts oramides depending upon the particular nature of the groups R¹ and R⁶present in the R²⁸, R²⁹, R³⁰ and R³¹ units. Again this can produce avery stable network or elastomeric material with robust physicalproperties. In addition to conductivity, these polymers will be capableof exhibiting third order polarisabilities and be suitable forapplications which employ the Kerr effect. These properties can beaffected or moderated when metals or metal ions are inserted into themacrocyclic heterocyclic unit. Suitable metal ions include sodium,potassium, lithium, copper, zinc or iron ions.

[0082] Materials such as the compounds of formula (X) and (XA) whichinclude metal ions such as copper might be particularly useful in theproduction of conducting layers for interconnects, useful in theproduction of say, 1000MHz or more microprocessors. Copper doping ofresin resists used as interconnects has been recognised as desirable bymuch of the electronics industry. By using a photopolymerizable materialin accordance with the invention in the production of suchmicroprocessors, reduce damage to substrate as compared to conventionalhardening processes would be expected. In addition, the processing timecould be reduced (conventional hardening processes typically requireheating at temperatures of 120-350° C. for between 10 and 30 minutes).This would therefore improve on batch yield from a wafer.

[0083] Yet a further possibility for the bridging group R¹⁶ is apolysiloxane network polymer where R¹⁶ comprises a straight or branchedsiloxane chain of valency r or a cyclic polysiloxane unit.

[0084] Examples of such compounds are compounds of structure (XI)

[0085] where R²⁴, R²⁵, R²⁸ and R²⁹ are as defined above in relation toformula (VIII), R³², R³³, R³⁴ are R³⁵, are as defined above in relationto formula (X) and in particular are each independently selected fromhydrocarbyl such as alkyl and in particular methyl, and each R³⁶ or R³⁷group is independently selected from hydrocarbyl or a group of formulaR²⁶-R³⁰ where R²⁶ and R³⁰ are as defined above in relation to formula(VIII), and u is 0 or an integer of 1 or more, for example of from 1 to20.

[0086] Other examples are compounds of formula (XII)

[0087] where R²⁴, R²⁵,R²⁶, R²⁷, R²⁸, R²⁹, R³⁰ and R³¹ are as definedabove in relation to formula (VIII) and R³², R³³, R³⁴ and R³⁵ are asdefined above in relation to formula (X). Although formula (XII) hasbeen illustrated with four siloxane units in the ring, it will beappreciated that there may be other numbers of such units in the cyclicring, for example from 3 to 8, preferably from 3 to 6 siloxane units.

[0088] In the above structures (XI) and (XII), it will be appreciatedthat —Si— may be replaced by B or B⁻; or —Si—O— is replaced by—B—N(R³⁹)— where R³⁹ is a hydrocarbyl group such as those defined abovein relation to group R³² in formula (XI) or a group -R²⁴-R²⁸ as definedin relation to formula (XII) above.

[0089] During stereolithography, compounds of formula (XI) and (XII) orvariants thereof, will form a cross-linked network where thecross-linking occurs through the groups R²⁸, R²⁹, R³⁰ and R³¹ asillustrated in FIG. 1. Such polymers may exhibit properties similar tothose of conventional siloxanes. However, in the case of compounds offormula (XI) and (XII), they may be used in stereolithography.

[0090] Further examples of compounds of formula (II) include compoundsof formula (XIII)

[0091] where R²⁴, R²⁵,R²⁶, R²⁷, R²⁸, R²⁹, R³⁰ and R³¹ are as definedabove in relation to formula (VIII).

[0092] Compounds of formula (II) are suitably prepared by conventionalmethods, for example by reacting a compound of formula (XV)

[0093] where X¹, Y¹, R², R³, R⁴, R⁵ and the dotted bonds are as definedin relation to formula (II), R^(1′) is a group R¹ as defined in formulaII or a precursor thereof, and R⁴⁰ is hydrogen or hydroxy, with acompound of formula (XVI)

R¹⁶−[R⁶−Z⁴]_(r)   (XVI)

[0094] where R⁶, R¹⁶ and r are as defined in relation to formula (II)and Z⁴ is a leaving group, and thereafter if necessary, converting aprecursor group R^(1′) to a group R¹.

[0095] Where a compound of formula (IIA) is produced, the compound offormula (XV) will be of formula (XVA)

[0096] where R^(1′), R², R³, R⁴, R⁵, R⁴⁰, X², X³, Y² and Y³ are asdefined above.

[0097] Suitable leaving groups Z⁴ include halogen in particular bromo,mesylate or tosylate. The reaction is suitably effected in an organicsolvent such as tetrahydrofuran, dichloromethane, toluene, an alcoholsuch as methanol or ethanol, or a ketone such as butanone and atelevated temperatures for example near the boiling point of the solvent.

[0098] Preferably the reaction is effected in the presence of a basesuch as potassium carbonate.

[0099] When the group R^(1′) is a precursor of the group R¹, it may beconverted to the corresponding R^(1 ′) group using conventionaltechniques. For example R^(1′) may be a nitrogen atom, which may beconverted to a group NR¹²(Z^(m−))_(1/m) where R¹², Z and m are asdefined above, by reaction with an appropriate salt under conventionalconditions. Examples of this are illustrated hereinafter.

[0100] Compounds of formulae (XV) and (XVI) are either known compoundsor they can be prepared from known compounds by conventional methods.

[0101] During stereolithography, the compounds link together by way ofthe multiple bond, in particular the diene group as illustrated inFIG. 1. Where the compounds used include more than one diene grouping,for example compounds of formula (II) where R is 2 or more, they willtend to become cross linked to form a network or three dimensionalstructure. The degree of cross linking can be controlled by carrying outthe polymerization in the presence of cross-linkers, where for example ris greater than 2, for example 4, or diluents. The latter will suitablycomprise a compound of formula (XVI)

[0102] where X¹, X², Y¹, Y², R¹, R², R³, R⁴, R⁵, R⁶, R¹⁶ and r are asdefined in relation to formula (II).

[0103] Stereolithographic compositions which include the compoundsdescribed above may also comprise other components. In general, theywill comprise a photoinitiator compound, and may additionally containfillers, extenders, stabilisers, radiation absorbers, polarisers,solvents or other monomers as required.

[0104] Suitable photointiators include 2,2′-azobisisobutyronitrile(AIBN), aromatic ketones such as benzophenones in particularacetophenone; chlorinated acetophenones such as di- ortri-chloroacetophenone; dialkoxyacetophenones such asdimethoxyacetophenones (sold under the Trade name “Irgacure 651”);dialkylhydroxyacetophenones such as dimethylhydroxyacetophenone (soldunder the Trade name “Darocure 1173”); substituteddialkylhydroxyacetophenone alkyl ethers such compounds of formula

[0105] where R^(y) is alkyl and in particular 2,2-dimethylethyl, R^(x)is hydroxy or halogen such as chloro, and R^(p) and R^(q) areindependently selected from alkyl or halogen such as chloro (examples ofwhich are sold under the Trade names “Darocure 1116” and “Trigonal P1”);1-benzoylcyclohexanol-2 (sold under the Trade name “Irgacure 184”);benzoin or derivatives such as benzoin acetate, benzoin alkyl ethers inparticular benzoin butyl ether, dialkoxybenzoins such asdimethoxybenzoin or deoxybenzoin; dibenzyl ketone; acyloxime esters suchas methyl or ethyl esters of acyloxime (sold under the trade name“Quantaqure PDO”); acylphosphine oxides, acylphosphonates such asdialkylacylphosphonate, ketosulphides for example of formula

[0106] where R^(z) is alkyl and Ar is an aryl group; dibenzoyldisulphides such as 4,4′-dialkylbenzoyldisulphide;diphenyldithiocarbonate; benzophenone; 4,4′-bis(N,N-dialkylamino)benzophenone; fluorenone; thioxanthone; benzil; or acompound of formula

[0107] where Ar is an aryl group such as phenyl and R^(z) is alkyl suchas methyl (sold under the trade name “Speedcure BMDS”).

[0108] Examples of fillers include inorganic particles and whiskers, forexample as described in U.S. Pat. No. 5,929,130. They are generallypresent in an amount of from 10-60% by weight of the composition.

[0109] Radiation energy absorbers where present, are typically presentin small quantities, for example from 0.001 to 1% by weight of thecomposition. The precise nature of the absorber will depend upon theparticular radiation being used and thus the wavelength of the radiationwhich is being controlled. Examples of such compounds includebenzotriazole compounds, benzophenone compounds, phenyl salycilates andcyanoacrylates, for example as described in U.S. Pat. No. 5,849,459.

[0110] Suitable solvents include organic solvents such as alcohols likeethanol so as to make the composition workable for use in astereolithographic process.

[0111] Other monomers, such as unsaturated urethanes of vinyl monomersmay also be present in the composition if they are photocurable. Thiswill result in the production of a copolymeric product which may havemodified properties. Suitably, the compound of formula (I) will comprisefrom 10 to 100% of the polycurable component of the composition.

[0112] Composites may also be produced by including in the compositionother moieties such as graphite, ethers such as crown ethers orthioethers, phthalocyanines, bipyridyls or liquid crystal compounds, allof which will produce composite polymers with modified properties.

[0113] Further additives which may be included in the compositionsinclude stabilisers such as additives intended to prevent shrinkage of athree-dimensional object obtained by stereolithography. Such additivesmay include components which are soluble in the composition but separatefrom the composition on hardening to form a different phase such asthose described in JP-A-3-20315. Polymeric coagulating materials whichcoagulate when heated such as those described in JP-A-3-104626 may alsobe included.

[0114] Other potential additives include polarising substances whichcontrol light irradiation. These may be helpful in ensuring that theoptimum balance is achieved between the use of high light energy (neededto allow the process to proceed rapidly) whilst maintaining a uniformpenetration depth. Examples of such compounds and their efficacy aredescribed for instance in JP-A-3-15520, JP-A-3-41126, JP-A-3-114732 andJP-A-3-114733 The compositions can be used in a variety of conventionalstereolithographic applications, for the production of three-dimensionalobjects such as plastic moulds, for example those used in the productionof prototype devices such as domestic electrical appliances etc.,intended for mass production.

[0115] The use of stereolithography compositions of the invention forthe formation of semi-conductor features would be advantageous in thatit would allow the formation of features on the substrate surfacewithout the use of conventional patterning methods that require severalprocess steps such as plasma etching and chemical etching. These twoprocesses, no matter how carefully done, cause some form of electricaldamage to the substrate itself and therefore increase the likelihood ofsource/drain and collector/drain leakage.

[0116] The production of semi-conductor features by curing ofcompositions of the invention would be beneficial, in particular if thelayer you are depositing is of a conducting or an insulating layer (apolyimide material based would have good insulating and capacitanceproperties for example). Again the amount of damage when removing theexcess from the unwanted areas of the substrate would be reduced, as asimple solvent clean should remove the uncrosslinked excess.

[0117] Thus the invention further provides a method of carrying out astereolithographic process to produce a three-dimensional object, saidmethod comprises use of a compound or a composition as described above.

[0118] Sterolithographic apparatus and conditions are well known in theart. Examples of suitable apparatus and systems are described inEP-A-250,121, U.S. Pat. Nos. 4,575,330 and 5,922,364 and a review of thearea is provided in Journal of Imaging Technology, 15:186-190 (190). Amethod for producing multilayer objects is described in U.S. Pat. No.4,752,498. Compounds of the invention may be used in any of thesetechniques, provided that appropriate curing radiation, in particularu.v. or electron beam radiation is used.

[0119] The method of the invention can be used in the preparation ofhomopolymers or copolymers where they are mixed with other monomericunits, which may themselves be of a similar basic structure, for exampleof formula (II) or otherwise.

[0120] A general scheme illustrating the sort of polymerization processwhich may occur using a polyethylene type bridging group is illustratedin FIG. 2.

[0121] Using the method of the invention, it is possible to take asuitable organic system that has optimal or optimised properties for usein certain applications, e.g. high yield strength, largehyperpolarisability, high pyroelectric coefficient, high conductivityetc, and to structurally modify the system so that it is possible topolymerize it using stereolithography. If functional groups areincorporated that will polymerize, it will become possible to create athree-dimensional network or plastic that will have propertiesassociated with the parent organic system.

[0122] Objects and particularly three-dimensional objects obtained usingthe method form a further aspect of the invention.

[0123] The production of compounds for use in the invention would beapparent to the person skilled in the art. Particular examples ofcompounds A are listed in Tables 2 to 7. TABLE 2

No. R⁷⁰ R⁷¹ Z 1 (CH₂)₁₀ H CF₃COO⁻ 2 (CH₂)₁₀ H PF₆ ⁻ 3 (CH₂)₁₀ H Cl⁻ 4(CH₂)₁₀ H I⁻ 5 (CH₂)₂ H PF₆ ⁻ 6 (CH₂)₁₂ CH₃ I⁻ 7 (CH₂)₁₀ H BF₄ ⁻ 8(CH₂)₄N⁺(CH₂CH═CH₂)(CH₂)₃— Br⁻ H Br⁻

[0124] TABLE 3

No. R⁷³ R⁷⁴ f g 9 CH₂O(CH₂)₂O(CH₂)₂OCH₂ H 0 0 10 CH₂O(CH₂)₂O(CH₂)₂OCH₂ H1 0 11 CH₂O(CH₂)₂O(CH₂)₂OCH₂ CH₃ 1 1 12 CH₂O(CH₂)₅OCH₂ H 1 0 13 (CH₂)₈ H0 0 14 CH₂(OCH₂CH₂)₁₂OCH₂ H 0 0 13 (CH₂)₈ H 1 0

[0125] TABLE 4

No. R⁷⁵ j k 14 CH₂(OCH₂CH₂)₁₂OCH₂ 1 1 15 (CH₂)₈ 1 1 16 (CH₂)₁₈ 1 1 17(CF₂)₁₀ 1 1 18 CH₂OCH₂CH₂OCH₂ 1 1 19

1 1  20⁺ (CH₂)₆ 1 1 21 bond 1 1 22 CH₂ 1 1

[0126] TABLE 5

No. R⁷⁶ R⁷⁷ Z 23 —CH₂CH═CH₂ CH₂CH═CH₂ Br⁻ 24 —(CH₂)₇CH₃ H Br⁻ 25—CH₂CH₂OH —CH₂CH₂OH Br⁻ 26 —(CH₂)₆OH H Cl⁻ 27 —CH₂CH═CH H PF₆ ⁻

[0127] TABLE 6

No. R⁷⁸ R⁷⁹ 28 C₆H₅ C 29 —(CH₂)5CH₃ C 30 —CH═CH₂ C 31 —(CH₂)₂COOH C 32—CF₃ C 33 —CH₂CN C 34 CH₃ S(O) 35 —CH₂N(CH₂CH₂OH)₂ C 36 —(CH₂)₃COOH C 37—CH₂Br C 38 —(CF₂)₃COOH C 39 (CH₂)₂COO⁻ ⁺NH(CH₂CH₂OH)₃ C 40 (CH₂)₂COO⁻⁺NH₃(C(OH)(CH₂OH)₂) C 41 —(CH₂)₂COO⁻ Li⁺ C 42 —(CH₂)₃COO(3-fluorophenyl)C 43 —C(═CH₂)CH₂COOH C 44 4-hydroxyphenyl C 45 —C(CH₃)═CHCOOH C 46—CH═C(CH₃)COOH C 47

C 48 —(CH₂)₃OH C 49 —(CH₂)₃OC(O)CH═CH₂ C 50 benzyloxy C 51—(CH₂)₃CONH(CH₂)₃Si(OCH₃)₃ C

[0128] TABLE 7 No. Structure 52

53

54

[0129] The preparation of these compounds is described in WO 00/06610.

1. The use of a compound of formula (A), which comprises a group ofsub-formula (I)

where R¹ is CR^(a′) where R^(a′) is hydrogen or alkyl, and R⁶ is a bond,or R¹ and R⁶ together form an electron withdrawing group; R² and R³ areindependently selected from (CR⁷R⁸) , or a group CR⁹R¹⁰, CR⁷R⁸CR⁹R¹⁰ orCR⁹R¹⁰CR⁷R⁸ where n is 0, 1 or 2, R⁷ and R⁸ are independently selectedfrom hydrogen or alkyl, and either one of R⁹ or R¹⁰ is hydrogen and theother is an electron withdrawing group, or R⁹ and R¹⁰ together form anelectron withdrawing group, and R⁴ and R⁵ are independently selectedfrom CH or CR¹¹ where R¹¹ is an electron withdrawing group; the dottedlines indicate the presence or absence of a bond, and X¹ is a groupCX²X³ where the dotted line bond to which it is attached is absent and agroup CX² where the dotted line bond to which it is attached is present,Y¹ is a group CY²Y³ where the dotted line bond to which it is attachedis absent and a group CY² where the dotted line bond to which it isattached is present, and X², X³, Y² and Y³ are independently selectedfrom hydrogen and fluorine; provided that at least one of (a) R¹ and R⁶or (b) R² and R³ or (c) R⁴ and R⁵ includes an electron withdrawing groupwhich is able to activate a cyclopolymerization reaction under theinfluence of radiation used in a stereolithographic process optionallyin the presence of a photoinitiator; in a stereolithographiccomposition.
 2. The use according to claim 1 wherein a group ofsub-formula (I) is a group of sub-formula (IA)

where R¹, R², R³, R⁴, R⁶, X², X³, Y² and Y³ are as defined in claim 1.3. The use according to claim 1 wherein the compound of formula (A) is acompound of formula of structure (II)

where X¹, Y¹, R¹, R², R³, R⁴, R⁵, R⁶ and the-dotted bonds are as definedin claim 1, r is an integer of 1 or more, and R¹⁶ is a bridging group,an optionally substituted hydrocarbyl group, a perhaloalkyl group or anamide, of valency r.
 4. The use according to claim 3 wherein thecompound of formula (II) is a compound of formula (IIA)

where X², X³, Y², Y³, R¹, R², R³, R⁴, R⁵, R⁶ and the dotted bonds are asdefined in claim 1 above, and r and R¹⁶ are as defined in claim
 3. 5.The use according to any one of the preceding claims wherein at least R¹and R⁶ form an electron withdrawing group.
 6. The use according to claim5 wherein in the compound, either (i) R¹ is a group N⁺R¹²(Z^(m−))_(1/m,)S(O)_(p)R¹³, B, P(O)_(q)R¹⁴ or Si(R¹⁵) where R¹², R¹³, R¹⁴ and R¹⁵ areindependently selected from hydrogen or hydrocarbyl, Z is an anion ofcharge m, p is 0, 1 or 2, and q is 1 or 2; and R⁶ is a bond; or (ii) R¹is a nitrogen atom and R⁶ is C(O) or S(O)₂; or (iii) R¹ is a CH groupand R⁶ is a group OC(O), C(O) or S(O)₂.
 7. The use according to any oneof the preceding claims wherein in the group of sub-formula (I), X², X³,Y² and Y³ are all hydrogen.
 8. The use according to any one of thepreceding claims wherein the compound of formula A is a compound offormula

where X¹, Y¹, R¹, R², R³, R⁴, R⁵, R⁶ and the dotted lines are as definedin claim 1, and R^(16′) is an optionally substituted hydrocarbyl group,a perhaloalkyl group or an amide.
 9. The use according to claim 8wherein the compound of formula (III) is a compound of formula (IIIA)

where X², X³, Y², Y³, R¹, R², R³, R⁴, R⁵ and R⁶ are as defined inrelation in claim 1, and R^(16′) is as defined in claim
 8. 10. The useaccording to any one of the preceding claims wherein the compound A is acompound of formula (IV)

where R^(16′) is as defined in claim
 8. 11. The use according to claim10 wherein in the compound of formula (IV), R^(16′) is optionallysubstituted alkyl, alkenyl, alkynyl or aryl group, wherein the optionalsubstituents are selected from halogen, hydroxy, carboxy or saltsthereof or acyloxy.
 12. The use according to claim 10 or claim 11wherein R^(16′) in formula (IV) is a perhaloalkyl group.
 13. The useaccording to claim 10 or claim 11 wherein R^(16′) is a dialkenylsubstituted amide, for example of sub formula (V)

where R¹⁸ and R¹⁹ are selected from groups defined above for R² and R³in claim 1, and R²⁰ and R²¹ are selected from groups defined above as R⁴and R⁵ in claim
 1. 14. The use according to any one of claims 1 to 9wherein the compound A is a radiation curable compound of formula (VI)

where z and m are as defined in claim 6, R²² and R²³ are independentlyselected from hydrogen and hydrocarbyl.
 15. The use according to claim 3or claim 4 wherein in compound A, r is greater than one.
 16. The useaccording to claim 15 wherein r is an integer of from 2 to
 8. 17. Theuse according to claim 3 or claim 4 wherein r is 2 and R¹⁶ is a group ofsub-formula (VII) —Z¹—(Q¹)_(a)—(Z²—Q²)_(b)—Z³—  (VII) where a and b areindependently selected from 0, 1 or 2, Z¹, Z² and Z³ are independentlyselected from a bond, an optionally substituted linear or branched alkylor alkene chain wherein optionally one or more non-adjacent carbon atomsis replaced with a heteroatom or an amide group, and Q¹ and Q² areindependently selected from an optionally substituted carbocylic orheterocyclic ring which optionally contains bridging alkyl groups. 18.The use according to claim 3 or claim 4 wherein R¹⁶ is an electricallyconducting chain.
 19. The use according to claim 18 wherein the compoundA is a compound of formula (VIII)

where R²⁸, R²⁹, R³⁰ and R³¹ are each groups of sub-formula (IX)

where R¹, R², R³, R⁴, R⁵ and R⁶ are as defined in claim 1 and R²⁴, R²⁵,R²⁶ and R²⁷ are independently selected from groups of sub-formula (VII)as defined in claim
 17. 20. The use according to claim 3 or claim 4wherein R¹⁶ is a tetra or octa substituted non-linear optic unit
 21. Theuse according to claim 20 wherein the compound A is a porphyrin compoundof formula (X)

where R²⁴, R²⁵, R²⁶, R²⁷ R²⁸, R²⁹, R³⁰ and R³¹ are as defined in claim17 and R³², R³³, R³⁴ and R³⁵ are each independently selected fromhydrogen or hydrocarbyl groups; wherein the compound optionally containsa metal ion within the macrocyclic heterocyclic unit.
 22. The useaccording to claim 20 wherein the compound A is a phthalocyaninecompound of formula (XA)

where R⁵⁰ through to R⁶⁵ are independently selected from hydrocarbyl, agroup OR⁶⁸ where R⁶⁸ is hydrocarbyl, halogen or a group R²⁴-R²⁸ whereR²⁴ and R²⁸ are as defined in claim 17, provided that at least two ofR⁵⁰ to R⁶⁵ are R²⁴-R²⁸ groups, and R⁶⁶ and R⁶⁷ are either hydrogen ortogether comprise a metal ion.
 23. The use according to claim 21 orclaim 22 wherein the compound contains a copper ion.
 24. The useaccording to any one of claims 21 to 23 for the production of conductinglayers for interconnects.
 25. The use according to claim 3 or claim 4wherein the bridging group R¹⁶ is a polysiloxane network polymer whereR¹⁶ comprises a straight or branched siloxane chain of valency r or acyclic polysiloxane unit.
 26. The use according to claim 25 wherein thecompound A is a compound of structure (XI)

where R²⁴, R²⁵, R²⁸ and R²⁹ are as defined above in claim 19, R³², R³³,R³⁴ are R³⁵, are as defined above in claim 21 and in particular are eachindependently selected from hydrocarbyl such as alkyl and in particularmethyl, and each R³⁶ or R³⁷ group is independently selected fromhydrocarbyl or a group of formula R²⁶-R³⁰ where R²⁶ and R³⁰ are asdefined above in relation to formula (VIII), and u is 0 or an integer of1 or more, for example of from 1 to
 20. 27. The-use according to claim25 where the compound A is a compound of formula (XII)

where R²⁴, R²⁵, R²⁶, R²⁷, R²⁸, R²⁹, R³⁰ and R³¹ are as defined above inclaim 19 and R³², R³³, R³⁴ and R³⁵ are as defined in claim 21; or amodified form of said compound with either 3 or 5 to 8 siloxane units.28. The use according to claim 3 or claim 4 where compound A has thestructure (XI) or (XII) as defined in claims 26 and 27 respectively butin which at least one —Si— group has been replaced by B or B⁻; or atleast one —Si—O— group has been replaced by —B—N(R³⁹)- where R³⁹ is ahydrocarbyl group or a group -R²⁴-R²⁸ as defined in claim
 17. 29. Theuse according to claim 3 or claim 4 wherein the compound A is a compoundof formula (XIII)

where R²⁴, R²⁵, R²⁶, R²⁷, R²⁸, R²⁹, R³⁰ and R³¹ are as defined above inclaim
 19. 30. The use according to any one of the preceding claims forthe formation of semi-conductor features.
 31. A stereolithographiccomposition comprising a compound as defined in any one of the precedingclaims, a photoinitiator compound, and at least one further componentselected from a filler, extender, stabiliser, radiation absorber,polariser, solvent or other monomers.
 32. A method of carrying out astereolithographic process to produce a three-dimensional object, saidmethod comprises (a) supporting a compound as defined in any one ofclaims 1 to 30 or a composition according to claim 31 on a surface, (b)irradiating said compound to produce a polymer therefrom, and (c)optionally applying further compound to thus formed polymer, andirradiating it, and (d) optionally repeating step (c) one or more timesto produce the desired three-dimentional object.
 33. A three dimensionalobject obtained by a method according to claim 32.